FASCIOLA HEPATICA : LIVER FLUKE WORM
CLASSIFICATION OF FASCIOLA HEPATICA : LIVER FLUKE WORM
PHYLUM :- PLATYHELMINTHES (Organ grade, acoelomate flatworms. )
CLASS :- TREMADOTA (Flukes, endo- or ectoparasites. )
ORDER :- DIGENEA (Two suckers, one or more intermediate hosts.)
FAMILY :- FASCIOLIDAE (Internal organs branched. )
GENUS :- Fasciola
SPECIES :- hepatica
GEOGRAPHICAL DISTRIBUTION
It has cosmopolitan distribution throughout sheep-raising areas. In U.S.A. and India it is endemic. Human Fascioliasis has been reported from Venezuela, Syria, China. Cuba, Argentina, U.S.S.R., Hungary, Rumania and France.
HABIT AND HABITAT
GENERAL CHARACTERSTICS OF FASCIOLA HEPATICA : LIVER FLUKE WORM
- Commonly known as sheep liver fluke.
- It is a polyxenous and pathogenic parasite.
- Body is leaf-like, dorsoventrally flattened measuring 18 to 51 mm in length and 4 to 15 mm in breadth. Fasciola gigantica is larger than F. hepatica.
- Anterior end is produced into a conical projection called cephalic cone.
- There is a small ventrally-placed mouth at the anterior extremity, surrounded by oral sucker.
- In both F. gigantica and F. hepatica, a little behind the mouth and oral sucker is an adhesive acetabulum or ventral sucker. Between oral sucker and ventral sucker is gonopore. Excretory pore is found at posterior extremity.
- Life-cycle involves two hosts. Sheep as definitive host and Limnea as intermediate host. Life-cycle stages include zygote, Miracidium larva, Sporocyst larva, Redia larva, Cercaria larva and encysted Metacercaria. Metacercaria after ingestion by sheep changes into adult parasite inside the host.
SPECIAL FEATURES
The liver fluke causes anaemia, eosinophilia, diarrhoea, dysentery, ulcers, pain, bottle-jaw disease and liver rot in sheep. The yield of wool, leather and meat is greatly reduced in infested sheeps causing great loss to animal products industry. It also causes metabolic disturbances in the host.
Preventive measures :- The snails in the pond should be collected and destroyed if they are contaminated. The water vegetation near the pond regularly examined for encysted metacercariae. Sheep and goat should not be allowed to graze on such contaminated vegetation and thus infection of liver fluke can be avoided by them.
IDENTIFICATION
The specimen contains cephalic cone, acetabulum and all above characters and hence it is F. hepatica.
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